Intramolecular Polarization-Mediated Solvation and Interphase Engineering for Low-Temperature High-Voltage Lithium...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium metal batteries (LMBs) face challenges with interfacial instability at anodes and cathodes under extreme conditions.
• Achieving simultaneous stability at cryogenic and high-voltage conditions is crucial for advanced LMBs.

Purpose of the Study:

• To develop a molecular strategy for regulating interfacial chemistry in LMBs.
• To enhance the stability and performance of LMBs under cryogenic and high-voltage conditions.

Main Methods:

• An intramolecularly polarized electrolyte with a significant dipole moment was designed.
• The electrolyte's effect on Li+ solvation dynamics, SEI, and CEI formation was investigated.
• Electrochemical performance was evaluated using Li||Li symmetric cells and full cells with LiNi0.8Co0.1Mn0.1O2 cathodes.

Main Results:

• The electrolyte demonstrated potential-dependent solvation screening, reducing Li+ desolvation energy and enabling anodic stability beyond 5.3 V.
• Dual-gradient interphases (LiF-rich SEI, boroxane-incorporated CEI) were formed, enhancing interface modulus.
• Li||Li symmetric cells achieved over 16,000 hours of stable cycling with minimal polarization.
• Full cells retained 90% capacity after 1000 cycles at 4.5 V and 80% at 4.9 V.
• 3 Ah pouch cells achieved high energy densities (509 Wh kg-1 at 30°C, 439.1 Wh kg-1 at -30°C).

Conclusions:

• The molecular polarization strategy effectively regulates interfacial chemistry for stable LMBs.
• This approach enables high-energy-density LMBs that operate reliably under extreme cryogenic and high-voltage conditions.
• The study presents a new paradigm for electrolyte and interphase engineering in next-generation batteries.